The effects of prophylactic anthelmintic treatment on the productivity of traditionally managed Djallonke sheep and West African Dwarf goats kept under high trypanosomosis risk.

The effects of a prophylactic anthelmintic intervention on the productivity of village based sheep and goats was studied in an area of high trypanosomosis risk in The Gambia during 2 and 3 years, respectively. In total, 223 sheep and 385 goats from five villages were included. Allocation to treatment groups (treated-control) was randomised by village, based on age and sex. Three treatments per rainy season were applied with Fenbendazole (Panacur, Hoechst, 2.5%, 5 mg/kg). Mean nematode egg excretion per gram faeces (EPG) of the treated groups were significantly reduced by prophylactic anthelmintic treatment, indicating the efficiency of the treatment despite the risk of rapid reinfestation. Weight gain benefits of anthelmintic treatment were observed in all age categories (> 6 month) of sheep but not in goats. Kidding rates were significantly increased whilst the same positive trends were observed for other reproductive parameters (litter size, parturition interval) in both goats and sheep without reaching statistical significance. Birth weights of offspring born out of treated does and ewes were higher (P < 0.05) than those from the controls. In contrast, growth rates until 3 months of age were not influenced by the treatment status of the dam. Mortality rates until the age of 3 months of kids from treated does were significantly lower than of those from control does. Mean Packed Red Cell Volume (PCV) levels during the rains were significantly higher in treated goats than in control goats. The same trend was observed in sheep. In general, there were no interactions between trypanosome infections and effect of anthelmintic treatment, thus both factors acted independently. Finally, the live weight productivity index (12 months old-offspring in kg/year per dam) for treated dams was 24% and 47% higher than in control ewes and does, respectively. It can be concluded that, despite the continuous risk of trypanosome infections which has a negative impact on their productivity, a beneficial effect of anthelmintic treatment was observed in both species but most obviously in goats, measured as an increased production and improved health status. A cost-benefit analysis should be carried out in order to confirm whether prophylactic anthelmintic treatment can be recommended to farmers to increase their income from small ruminant production. Nevertheless, anthelmintic treatment will certainly optimise the trypanotolerance in these breeds.